Predicting and simplifying which pathogens may spill over from animals to humans is a major priority in infectious disease biology. Many efforts to determine which viruses are at risk of spillover ...use a subset of viral traits to find trait-based associations with spillover. We adapt a new method-phylofactorization-to identify not traits but lineages of viruses at risk of spilling over. Phylofactorization is used to partition the International Committee on Taxonomy of Viruses viral taxonomy based on non-human host range of viruses and whether there exists evidence the viruses have infected humans. We identify clades on a range of taxonomic levels with high or low propensities to spillover, thereby simplifying the classification of zoonotic potential of mammalian viruses. Phylofactorization by whether a virus is zoonotic yields many disjoint clades of viruses containing few to no representatives that have spilled over to humans. Phylofactorization by non-human host breadth yields several clades with significantly higher host breadth. We connect the phylogenetic factors above with life-histories of clades, revisit trait-based analyses, and illustrate how cladistic coarse-graining of zoonotic potential can refine trait-based analyses by illuminating clade-specific determinants of spillover risk.
Nipah virus (NiV) is a zoonotic virus that can pose a serious threat to human and livestock health. Old-world fruit bats (
Pteropus spp.
) are the natural reservoir hosts for NiV, and
Pteropus lylei
..., Lyle’s flying fox, is an important host of NiV in mainland Southeast Asia. NiV can be transmitted from bats to humans directly via bat-contaminated foods (i.e., date palm sap or fruit) or indirectly via livestock or other intermediate animal hosts. Here we construct risk maps for NiV spillover and transmission by combining ecological niche models for the
P. lylei
bat reservoir with other spatial data related to direct or indirect NiV transmission (livestock density, foodborne sources including fruit production, and human population). We predict the current and future (2050 and 2070) distribution of
P. lylei
across Thailand, Cambodia, and Vietnam. Our best-fit model predicted that central and western regions of Thailand and small areas in Cambodia are currently the most suitable habitats for
P. lylei
. However, due to climate change, the species range is predicted to expand to include lower northern, northeastern, eastern, and upper southern Thailand and almost all of Cambodia and lower southern Vietnam. This expansion will create additional risk areas for human infection from
P. lylei
in Thailand. Our combined predictive risk maps showed that central Thailand, inhabited by 2.3 million people, is considered highly suitable for the zoonotic transmission of NiV from
P. lylei
. These current and future NiV transmission risk maps can be used to prioritize sites for active virus surveillance and developing awareness and prevention programs to reduce the risk of NiV spillover and spread in Thailand.
Interest in bat-borne diseases and parasites has grown in the past decade over concerns for human health. However, the drivers of parasite diversity among bat host species are understudied as are the ...links between parasite richness and emerging risks. Thus, we aimed at exploring factors that explain macro and microparasite species richness in bats from Southeast Asia, a hotspot of emerging infectious diseases. First, we identified bat species that need increased sampling effort for pathogen discovery. Our approach highlights pathogen investigation disparities among species within the same genus, such as Rhinolophus and Pteropus. Secondly, comparative analysis using independent contrasts method allowed the identification of likely factors explaining parasite and viral diversity of bats. Our results showed a key role of bat distribution shape, an index of the fragmentation of bat distribution, on parasite diversity, linked to a decrease for both viral and endoparasite species richness. We discuss how our study may contribute to a better understanding of the link between parasite species richness and emergence.
1. The management of migratory species is challenging because of insufficient data on long-range movement patterns, habitat use, and the impact of anthropogenic pressures (e.g. hunting) throughout ...their home ranges. 2. We evaluate the current abundance and mobility of the Malayan flying fox Pteropus vampyrus, a threatened fruit bat species of ecological and economic significance across Southeast Asia, using roost site surveys and satellite telemetry. We combined this with data from hunter license sales and population projection models to assess the impact and sustainability of current hunting practices in Peninsular Malaysia. 3. We monitored 33 active Pteropus vampyrus roost sites in Peninsular Malaysia, including eight seasonal roost sites. Roost site occupancy showed considerable temporal variation over the 3-year study period. 4. Hunting activity has more than doubled since 1996, and based on license sales, we estimate that a minimum legal harvest of 87 800 bats occurred between 2002 and 2005. Population models suggest that this level of hunting is likely to be unsustainable given our baseline abundance scenarios of 100 000, 250 000 or 500 000 bats, especially considering that these models do not include culling of Malayan flying foxes as agricultural pests or illegal hunting activities, for which there are no available data. 5. Satellite telemetry of seven adult male bats show that Malayan flying foxes are highly mobile, travelling hundreds of kilometres between roosting sites within a year and occupying home ranges that extend beyond Malaysia to include Indonesia and Thailand. We conclude that focal hunting pressure in Malaysia threatens a regional population of this migratory mammal. 6.Synthesis and applications. This is the first study of its kind on flying foxes in Asia, and illustrates that bats, like other migratory species, urgently require comprehensive protection by regional management plans across their range. P. vampyrus moves across international borders in Southeast Asia. Current hunting practices within Malaysia together with limited protection in other countries may threaten its long-term survival.
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•Molecular Nycteria parasite phylogeny reveals two distinct Nycteria/bat assemblages.•Robust prevalence and gametocytemia of Nycteria infections were found in insectivorous ...bats.•Phylogenetic signatures of ancient Nycteria host-parasite congruence.•Molecular evidence is given for additional members in Nycteria spp. complex.
Parasitic protozoan parasites have evolved many co-evolutionary paths towards stable transmission to their host population. Plasmodium spp., the causative agents of malaria, and related haemosporidian parasites are dipteran-borne eukaryotic pathogens that actively invade and use vertebrate erythrocytes for gametogenesis and asexual development, often resulting in substantial morbidity and mortality of the infected hosts. Here, we present results of a survey of insectivorous bats from tropical Africa, including new isolates of species of the haemosporidian genus Nycteria. A hallmark of these parasites is their capacity to infect bat species of distinct families of the two evolutionary distant chiropteran suborders. We did detect Nycteria parasites in both rhinolophid and nycterid bat hosts in geographically separate areas of Sub-Saharan Africa, however our molecular phylogenetic analyses support the separation of the parasites into two distinct clades corresponding to their host genera, suggestive of ancient co-divergence and low levels of host switching. For one clade of these parasites, cytochrome b genes could not be amplified and cytochrome oxidase I sequences showed unusually high rates of evolution, suggesting that the mitochondrial genome of these parasites may have either been lost or substantially altered. This haemosporidian parasite-mammalian host system also highlights that sequential population expansion in the liver and gametocyte formation is a successful alternative to intermediate erythrocytic replication cycles.
BACKGROUND: Bats are reservoirs for a diverse range of coronaviruses (CoVs), including those closely related to human pathogens such as Severe Acute Respiratory Syndrome (SARS) CoV and Middle East ...Respiratory Syndrome CoV. There are approximately 139 bat species reported to date in Thailand, of which two are endemic species. Due to the zoonotic potential of CoVs, standardized surveillance efforts to characterize viral diversity in wildlife are imperative. FINDINGS: A total of 626 bats from 19 different bat species were individually sampled from 5 provinces in Eastern Thailand between 2008 and 2013 (84 fecal and 542 rectal swabs). Samples collected (either fresh feces or rectal swabs) were placed directly into RNA stabilization reagent, transported on ice within 24 hours and preserved at −80°C until further analysis. CoV RNA was detected in 47 specimens (7.6%), from 13 different bat species, using broadly reactive consensus PCR primers targeting the RNA-Dependent RNA Polymerase gene designed to detect all CoVs. Thirty seven alphacoronaviruses, nine lineage D betacoronaviruses, and one lineage B betacoronavirus (SARS-CoV related) were identified. Six new bat CoV reservoirs were identified in our study, namely Cynopterus sphinx, Taphozous melanopogon, Hipposideros lekaguli, Rhinolophus shameli, Scotophilus heathii and Megaderma lyra. CONCLUSIONS: CoVs from the same genetic lineage were found in different bat species roosting in similar or different locations. These data suggest that bat CoV lineages are not strictly concordant with their hosts. Our phylogenetic data indicates high diversity and a complex ecology of CoVs in bats sampled from specific areas in eastern regions of Thailand. Further characterization of additional CoV genes may be useful to better describe the CoV divergence.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Historic and contemporary host ecology and evolutionary dynamics have profound impacts on viral diversity, virulence, and associated disease emergence. Bats have been recognized as reservoirs for ...several emerging viral pathogens, and are unique among mammals in their vagility, potential for long-distance dispersal, and often very large, colonial populations. We investigate the relative influences of host ecology and population genetic structure for predictions of viral richness in relevant reservoir species. We test the hypothesis that host geographic range area, distribution, population genetic structure, migratory behavior, International Union for Conservation of Nature and Natural Resources (IUCN) threat status, body mass, and colony size, are associated with known viral richness in bats. We analyze host traits and viral richness in a generalized linear regression model framework, and include a correction for sampling effort and phylogeny. We find evidence that sampling effort, IUCN status, and population genetic structure correlate with observed viral species richness in bats, and that these associations are independent of phylogeny. This study is an important first step in understanding the mechanisms that promote viral richness in reservoir species, and may aid in predicting the emergence of viral zoonoses from bats.
In 2008-09, evidence of Reston ebolavirus (RESTV) infection was found in domestic pigs and pig workers in the Philippines. With species of bats having been shown to be the cryptic reservoir of ...filoviruses elsewhere, the Philippine government, in conjunction with the Food and Agriculture Organization of the United Nations, assembled a multi-disciplinary and multi-institutional team to investigate Philippine bats as the possible reservoir of RESTV.
The team undertook surveillance of bat populations at multiple locations during 2010 using both serology and molecular assays.
A total of 464 bats from 21 species were sampled. We found both molecular and serologic evidence of RESTV infection in multiple bat species. RNA was detected with quantitative PCR (qPCR) in oropharyngeal swabs taken from Miniopterus schreibersii, with three samples yielding a product on conventional hemi-nested PCR whose sequences differed from a Philippine pig isolate by a single nucleotide. Uncorroborated qPCR detections may indicate RESTV nucleic acid in several additional bat species (M. australis, C. brachyotis and Ch. plicata). We also detected anti-RESTV antibodies in three bats (Acerodon jubatus) using both Western blot and ELISA.
The findings suggest that ebolavirus infection is taxonomically widespread in Philippine bats, but the evident low prevalence and low viral load warrants expanded surveillance to elaborate the findings, and more broadly, to determine the taxonomic and geographic occurrence of ebolaviruses in bats in the region.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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